On the status bar, along the bottom of the window, there's a button for setting object snap modes. (If you don't have a status bar, type the command STATUSBAR and change it from 0 to 1 [0=off, 1=on].) Button designs change from one version to the next, so I'm not sure what you'll see*. In my version (2014), it's a square with a spark in the top left corner. If you only click on the button, you turn the entire object snap system on and off. If you right click on that button, you will see a list of snaps so you can choose which one to turn on/off. That list also includes a Settings option, which opens the Object Snap dialog (you can open that same dialog with the command _OSNAP). The dialog box lists all the available snap modes in one place and lets you toggle them on and off. Once you hit OK, the settings remain in place until the next time you change them. Some snap settings only last for the duration of a command.
You'll find that AutoCAD usually has several methods for doing the same thing. It's confusing at first, but you'll appreciate the flexibility it gives you. For instance, some prefer the ribbon, some the mouse, some the keyboard. Once you've learned the basics, you can decide what works best for you.
Unfortunately, AutoCAD has a steep learning curve. Once you've got your feet underneath you, though, you will have a lot of power.
*They claim the meanings of these icons are "self-explanatory." If that's so, why do they change every year?